Install a subwoofer inside iMac 27"

Well the tittle says it all, my idea is to install a subwoofer inside my 27" iMac.

Originally I thought about doing this with a Powerbook subwoofer but what laptop ever had a good bass right?

So I want to get one of these little smartphones' sub they sell around:

And built a custom enclosure that would conceivable fit alongside the HDD, perhaps made out of cardboard or maybe grab some small plastic container, not sure yet (before/after pictures - not my computer though):

The 'box' should look something like this (obviously not on scale):

But the thing is: where and how to power this thing?

I could run one wire from each side speaker (say negative from left speaker and positive from the right one) but would it short the board?

And even if it doesn't short the board I don't really understand how sound systems work so how should it be done in order to get the best bass? Will I need some resistor, something of the sort?

Any suggestions that doesn't include 'buy a separate sound system' or nothing like that? I do want to hack this, that is the sole purpose of this topic.

Already replaced the i5 for an i7, the DVD-ROM for a SSD dock, installed some copper plates between the video card memory chips (there were A LOT of thermal paste in there to breach the gap!) and now I want to hack a subwoofer inside it. Simple as that :)

Thanks!!

Update (07/16/2017)

Checking some pictures online before I crack it open again I realised there is no gap under the heatsink bracket to fit anything.

There is a gap under the DVD-ROM, not sure if it'll be enough though:

So if I choose to continue it will try to fit it in this spot:

On the bright side I remembered there are 2 sets of speakers on each side, one supposed to be for bass already. So if I go on with this I'll figure it out which ones are the bass lines and that is were I'll get the wiring to use on my hack (negative from left/positive from right):

Update (07/17/2017)

Yet a new design.

Not enough room to work with, decided to use a smaller box with a laptop's subwoofer, perhaps two. Might even look for some Apple subs from another iMac…

And since the box is going to be smaller - same about the speakers - I thought about adding another 'loop' inside the box to improve lower frequencies (?).

Will try to post picture of a prototype minus subs. As expected laptop subs will be quite difficult to find the right one…

Update (07/18/2017)

I've made 3 prototypes:

-the first one made out of a soap box according to drawing below. It was too big so I tested as a iPhone dock instead and it seemed to have dampened higher frequencies but nothing more - I didn't expect anything else anyway.

-the second one was also made out of a soap box, a bit smaller and following drawing below. I thought it was too thin and too wide so I didn't finish it because I had another idea that I thought would be better.

-the third prototype was made out of a toothpaste box + coffee cup with the corners 'rounded up' using toilet rolls. So with that last change I've reduced the width at the same time increasing the height and length.

Inside it looks a bit like this

The actual thing look like this

I realise nothing looks refined - they called this sort of mod 'ghetto' in my early days modding hardware :P - and of course it doesn't look refined after all I'm using Preview to make the drawings and whatever cardboard I find at home to build this thing but as long as it works I don't care, it'll stay inside the computer anyway ;)

Now still looking for a suitable mini-sub to finally install and test it :)

Update (07/18/2017)

Got myself a tiny sub/speaker:

Preliminary tests were made using the same music, same volume, recorded at the same place on my desk.

Results were not encouraging though…

Between first and second video (original setting vs prototype) seems to have produced a little increase in lower frequencies. Might get even better once the box gets sealed properly.

Third video shows appalling audio - everything is barely audible.

Issues found:

1) Needs to be mounted inverted as it won't fit inside the box. Primarily it means better use of airflow inside the box but I'm not 100% comfortable leaving metal parts exposed being this a hack to be installed VERY close to my HDD and in a VERY confined space;

2) To produce the results I am looking for I will need to use its tiny amp. It is USB powered so I could block one USB port and use it to power it up, but again this kind of mod I'm not 100% comfortable with.

It is doable, I can certainly do it but the further I go into the rabbit hole the more the risks keep increasing as now I would have to tap into the original speaker's output + tap into one USB port to power this thing up.

The chances of shorting the whole main board would be greater and probably not worth it.

Will have a deep thought about it. If I do decide to go further I'll post it here after it's done but at the moment it is highly unlikely…

Here are the videos anyway:

-Original (amped)

-Prototype (amped)

-Prototype (no amp)

Update (07/19/2017)

Finished!

After having the box completely sealed I managed to get a bit more 'kicks' out of it. It's hard to notice because I'm still using just the regular AUX from my iPhone but you can hear that the higher frequencies got obviously muffled and the lower frequencies sound a bit deeper.

But I still don't like it…

I don't like to have the speaker inverted, I don't like that I kept the battery inside taking all that space (when I removed the battery it refused to work), I don't like that I was lazy and didn't even tried to replace the battery with the USB wiring and I'm not sure that cone on the exit is really doing anything good…

Will destroy this one to remove the parts and build another, this time with the speaker inside, no battery, no cone and perhaps keep the mini-amp on the outside.

Might even change the box's layout from horizontal TL to vertical TL - or is it the other way around? :P

Anyway, pic and vid :)

Update (08/07/2017)

Finished [for real now haha]

I'm aware it doesn't look Apple-pretty but it seems to work :)

Now the idea is to solder the speaker connector into the iMac's subs (assuming the big ones are subs) and the other connector into the 'last' USB port which I'll try to somehow block from external use.

Will post more pictures and close the thread once it's installed :)

Video - keep in mind it's plugged into my iPhone so all frequencies are going through not just bass:

Update (09/01/2017)

So once I figured it out the black speaker cables are the ones used for bass I got everything prepped on my logic board to install the subwoofer

But I decided to have my DVD back instead of a caddy for my SSD once I saw the guide to install the SSD underneath the DVD.

That meant more cables and those cables got in the way where I was planning to install the subwoofer

So I had to redo the whole thing all over again and installed in 'above' the HDD

But it wouldn't work!

It turns out the logic board doesn't 'like' to have another speaker sharing both left/right outputs and that meant the subwoofer and one of the speakers wouldn't work in this setup.

Now I was facing the choice of scraping the whole thing or making it a mono output.

Instead I decided to buy 2 other speakers and will make it twice the setup I had planned before. Just waiting for the ordered speakers to be delivered and then there will be more pictures and a end to this story :)

Update (10/15/2017)

So I've tried a few different 2 speakers designs trying to find something that would fit.

Found one but upon testing the sound wasn't great but ok, lets do it.

I finished but it wouldn't work. This is the only sound - noise really - that would come out of it.

And after all this I noticed the frustration was getting the best of me and decided to terminate the idea before I ended up damaging something I couldn't repair.

And that was that. Disassembled/unsoldered everything and tossed in the bin.

I still believe it can be done but it definitely needs more knowledge than what I have to figure it out what went wrong then do it right. And perhaps find a better design one that would get better sound out of tiny speakers - that cylinder was the best one but wouldn't fit.

Late edit:

1) I was thinking of trying again but without the amplifier. Just plug the speakers along with the original bass speakers and see what happens.

Far from the original idea and would get louder results at best (the idea was to get better bass, not louder sound) but I already got the parts anyway…

2) This is bad news but one that makes me want to open it up again: when I tried to 'force fit' the cylinder design it seems I bent the display a bit. nothing horrible, barely noticeable, but might want to fix it if I decide to try the speakers one last time…

1 Respuesta

How are you planning on driving it? Tapping the speaker wires won't get you the needed output for the subwoofer. You'll need an Amp which offers a subwoofer output (your mac's DAC does not offer one). So you'll need to find an Amp and then figure out how to power it and then tap into the internal speakers as well as mounting it internally. I don't think there is enough room for it and you still have additional heat from the Amp.

The other problem you face here is the vibration of the Bass, HDD's are like phonograph records. But, instead of a needle riding a groove it's a magnetic head just skimming the platter. Surprisingly, the percussion of the bass sound can be enough to push the head into the platter or cause the head to misalign (X,Y & Z axis between the two). Thats why you see the drive mounted in rubber so the low frequencies and bangs don't mess up the drive. With your subwoofer mounted internally you run the risk of damaging your HDD and other types of vibration damage directly from the air percussion.

The last issue is space the larger the diaphragm the deeper the bass. Even with a good box design the space internally is so limited I don't think you can get the better bass you are looking for internally.

Sadly, I think it drives us back to doing this all externally. Using a good USB DAC with Amp you can drive your external speakers and subwoofer and make the whole house shake!

I don't want to make the HDD - or the house lol - shake. The current speakers inside are already good enough for me what I do want is to get better bass out of it which lacks a lot.

Tried Boom and it helped, but still not enough to enjoy movies, TV shows and even my MP3…

As far as AMPs it's a no-go. No room, don't want to f*** around with the power supply to find out were to draw power from and the heating could be directed from the HDD fan but I don't want to go there either.

Tapping in the original speakers wires might work though. There are 2 sets of speakers, 1 set seems to be for bass - once I can figure it out which is which I will use the bass line one wire from each like said above.

What I did so far was to build a box out of a soap box and plan on fill it up with some loose cotton thinly spread then attach a coffee cup at the end with some inside curves (?) at the connection with the box then straight cone as exit.

Can't seem to be able to attach images here but it's smaller than a SSD and just about 1/3 thicker. Haven't done the cone exit yet, will update OP as soon as I get the full setup - speaker included - ready and tested but not yet installed :)

Recursos

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Mantente al tanto

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